
where \(J(\theta )\)  is given by taking \(S(v_{\rm rel};*{X})=1\) . While
the Sommerfeld effect hardly changes the J-factor, the annihilation
cross section is significantly affected by it, which was shown by
Refs. [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}. The
photon spectrum by the Wino annihilation is given by
\(\sigma v \frac{dN_\gamma }{dE}=\sum _i (\sigma v)_i \left[\frac{dN_\gamma }{dE}\right]_i\,.\) 
